Hydraulic power brake unit



c':.w.sPA-| D1NG ETAL 2,908,137 HYDRAULIC POWER BRAKE UNIT ocr. 13, 1959Filed Feb. 12, 1957 l power source. w

liquid pressure pump 90 that supplied liquid under pressure through theconduit 31 to an inlet fitting 82 that 1s disposed in an inlet port 83in the housing wall, the port 83 being connected by means of a passage84 with the annular spacel around the plunger 35 Awhereby liquld underpressure is delivered tothe servomotor 10.

.The pressure accumulator 12 has a piston 100 therein carrying theyO-ring seals 101. The piston divides ,the cylinder bore 30 of theaccumulator into a liquid pressure chamber 102 and a gas pressurechamber k103. The gas pressuretchmber 103 is chargedwith a predeterminedY of the member 31 and the piston plunger 14 ofthe master t gaseouspressure through the charging fitting 104 that is closedby a cap 105after the gaseous pressure charge is applied within the chamber 103.When the liquid pressure chamber 102 is empty, at the time the gaspressure is applied into the chamber '103, the piston 100,will be in aleft hand position. The sleeve 105' in the chamber 103 limitsthemovement of the piston 100 in a right hand direction. t a Y The liquidpressure chamber 102 of the accumulator 12 connects with the pressureinlet port 83 by means of a passage 106 so that when liquid underpressure is sup@ plied from thepump 90, the chamber 102 of the pressureaccumulator will be lilled with liquid to urge the'pi'ston into theposition shown Vin the drawing against the pressure of the gas vin thechamber 103 and thereby establish a predetermined volume of liquid inthe chamber 102 that can be usedrby the servo motor 10 in theevent thepressure source. 90 shouldlrfail, the expansiontof the gas in i thechamber 103 provides for the desired pressure de;-

liveryy of liquid from the chamber 102 to the servomotor for actuationthereof. v 1 t To prevent loss of fluid pressure from the chamber 102 ifthe pressure'source or pump 90 should fail for any reason, a check valve110 is provided in the inlet port 83 which closes the conduit 81whenever thepressure in t that conduit is below the pressure lin thechamber 102.

' that a vacuum would `be tended Vto be pulled in the work'.

chamber 36 since. there is Vno fluid under pressuretavaib able from Vtheysource 90. Toprevent this action a cross. owpassage 120 isv providedbetween the outlet port 76 rection upon its seat so long as liquid`pressure exists in the-port 83 either from the source 90 or from thepres.- sure chamber 102 ofthe accumulator 12.

Y However,l when there isno liquid pressure in the inn let portr83because of failure of the pump 90 and an eX-v haustion of uid underpressure from the accumulator 12,

, the check valve 121 can open and allow tluid to flow from theexhaustchambery 37 'of the servomotor through the passage 75, and thence fromthe outlet port .'76 tothe inlet port 83 and thence to the work chamber36 through the ports*and.passagesr69,67, 68, k64, and 63. This crossflow vof liquid prevents a'vacuum being drawn in cham# ber, 36 andthereby eliminates any possibility otretard-V rection, the actuating rod49 moves the member 47 forwardly to close the exhaust port 70 and openthe port 68.y to allow liquid under pressure to be supplied to the workChamber 36 and thereby eiect a power movement of the plunger 35; in aright hand direction for power actuation cylinder 11." When the operatordesires to stop the brake action, liquid under pressure will be suppliedto the work chamber 36 until the port 68 is closed, at which time port70 Ywill Yalso be closedV andpth'erebyretain'the brake application ina'hold position.

When the brakes are to'be released movement of the actuator 47 in a lefthand directionby the foot pedal 48 will open the exhaust port 70andallow fluid under Y pressure to be exhausted from the work chamberV36 in a manner heretofore referred to.

While the form of embodiment offthe invention as herein disclosedconstitutes a preferred form, it is` to be understoodthat other formsmight beadoptedrtas may come within the scope of the claims Whatis'claimed is 'as follows:

actuating the brakes of a vehicle, comprising a liquid a pressureactuated servomotor including a ycylindervhaving a plunger movable inthe cylinder' dividingthe cylinder into two chambers one being V*apressurev work chamber! andthefother being an exhaustchamber, a'V valvedevice in said plunger spring urged in one direction normallly'to closea liquid pressure inlet passage communicating with said work Achamberand open an exhaustpassage connect- Y ing said work chamber with'saidexhaust chamber; means forming a pressure accumulator chamber adjacentsaid servomotor and including-.passage means connecting the accumulatorchamber with said inlet passage, means` forming :an outlet passage fromsaid exhaust chamber; and means- :tormmga cross flow passage connectingsaid outlet passage with said inlet passage and including' check valvemeans in vsaid cross ow passage to prevent inter- "connection of theinlet and outlet-passages solong as 50 and the inlet port 83 witha checkvalve 121 being located in the port 120 that isnormally urged Vin a lefthandzdiliquid pressure exists in the inlet passage.

, 2. A hydraulically operated power unit adapted for actuating thebrakes lof a vehicle,k comprising; a liquid pressure actuated servomotor including a'cylinder having a plunger movable in the cylinderdividing Vthe cyling der 1nto two chambers one being apressre workchamber and the other being Yan exhaust chamber, a valvedevice lnrsardplungerl spring urged in one -directiontnormally to close' a liquidpressure inlet passage communicating withsaid work chamber and open anexhaust passage con` nectrng said work chamber with said exhaustchamber; means forming a-tpre'ssure accumulator chamber adjacent [said4s ervon'rotor andtincluding passage meansconnectlng :the accumulatorchamber with saidV inlet passage,

means forming an outlet passage'fromk said exhaust cham`V ber,meansfo-rrning across flow passage connecting said outletsV passageswith' said inlet passage and yincluding a check valvemeans Yinvs'aidcross flow passage to prevent interconnection of the inlet and outletpassages so long ing of movement of the master cylinder during a manu#al operation resulting from a loss ofl power from the In the normaloperationso'flthe devicetfluid lin theworkf. A chamber 36 willfbeconnected with the outlet port 76V t through 'thepassages 'and chambers63, 64,V 71, 70, 675,

37 and 75` the brakes being in aureleased position.

Whenthebrakes are .to be ,applied by movementy v themaster cylinderVpistonplunger 14S in' a right hand dias liquid pressure exists in theinlet passage; and-'additional cheek valve means in said inletrpassageto prevent loss of iiuidtpressure from said accumulator ywhen uid YpressureV failsgbetween the last mentioned check Vvalve andi the sourceof uid pressure t t t L 3; Aj hydraulically operated power unit adaptedfor actuating the brakes of a vehicle, comprising; ,a liquid pressurelactuated servo motor including a cylinder having a plunger movable inthe cylinder dividing :the cylinder,V j into two chambersone beingapressure work chamber and the other-'being an exhaustchamber, Y avalvedevice in said plunger spr-ingvurged in onedirection normally said inletpassage and including check valve means in` said cross flow passage toprevent interconnection of the inlet and outlet passages so long asliquid pressure exists in the inlet passage.

4. A hydraulically operated power unit for actuating the brakes of avehicle, comprising; a liquid pressure actuated servo motor including acylinder having a plunger movable in the clinder dividing the cylinderinto two chambers one being a pressure work chamber and the other beingan exhaust chamber, a valve device in said plunger spring urged in onedirection normally to close a liquid pressure inlet passagecommunicating with said work chamber and open an exhaust passageconnecting said work chamber with said exhaust chamber; means forming apressure accumulator cylinder adjacent to and parallel with said servmotor having piston means therein dividing said cylinder into a liquidpressure chamber and a gas pressure chamber and movable in the cylinderby action of the gaseous pressure in fthe gas pressure chamber to retainliquid inthe liquid pressure chamber under pressure of the gas in thegas pressure chamber and including passage means connecting the liquidpressure chamber with said inlet passage; means forming an outletpassage tfrom said exhaust chamber; and means forming a cross ilowpassage connecting said outlet passage with said inlet passage andincluding check valve means in said cross ow passage toqpreventinterconnection of the inlet and outlet passages so long as liquidpressure exists in the inlet passage.

5. A hydraulically operated power unit for actuating the brakes of avehicle comprising, a housing having iirst and second cylinder meanseach closed at both ends thereof, a plunger slidable in said irstcylinder means and dividing said cylinder means into rtwo chambers onebeing a pressure work chamber and the other being an exhaust chamber, avalve device in said plunger spring urged in one direction normally toclose a pressure inlet passage communicating with said work chamber andopen an exhaust passage connecting said work chamber with said exhaustchamber, a plunger slidable in said second cylinder means and dividingthe same into two chambers one being a liquid pressure chamber and theother being a gas pressure chamber, passage means in said housingconnecting the said liquid pressure chamber of said second cylindermeans with said inlet passage for supply of liquid under pressure tosaid work chamber of said first cylinder means, an outlet passage insaid houisng from said exhaust chamber, and a cross ow passageconnecting said outlet passage with said inlet passage and includingcheck valve means in said cross ow passage to prevent interconnection ofthe inlet and outlet passages so long as liquid pressure exists in theinlet passage.

References Cited in the ile of this patent UNITED STATES PATENTS1,960,996 Guernsey May 29, 1934 2,170,890 Allen Aug. 29, 1939 2,343,698Parnell Mar. 7, 1944 2,359,949 Van Der Werff Oct. 10, 1944 2,409,335 VonStackelberg Oct. l5, 1946 2,661,597 Edge Dec. 8, 1953 2,775,957 AndersonJan. 1, 1957

